Aa and b, representative ST maps showing the effect of 1 μm FPL 64176 on Ca2+ transient firing in USMCs. Ba–d, summary data showing the effect of 1 μm FPL 64176 on USMC Ca2+ transient frequency (a), amplitude (b), duration (c) and spatial spread (d) (c = 18, n = 6). C, representative ST map showing the effect of rapidly applying 1 μm FPL 64176 to USMC Ca2+ transients. Da and b, representative ST maps showing the effect of 1 μm isradipine on Ca2+ transient firing in USMCs. Ea–d, summary data showing the effect of 1 μm isradipine on USMC Ca2+ transient frequency (a), amplitude (b), duration (c) and spatial spread (d) (c = 14, n = 4). ns, not significant.